For some reason I can't remember the great character actor that was on Lucy occasionally, and countless other shows also.
He was the conductor on the train, or he worked in a store. He always said WWEEELLL and Oh Know and other phrases with a great look on his face

Frank Nelson.

The actor you're thinking about is Frank Nelson. He played many characters in I Love Lucy such as a game show host "Freddy Filmore", a waiter, a sargent, a TV host, a talent scout, a train conductor, a plane conductor, and Lucy's nieghbor "Ralph Ramsey".

He appeared in these episodes:
episode #5- "The Quiz Show"
episode #32- "Lucy Gets Ricky On the Radio"
episode #56- "Lucy Changes Her Mind"
episode #66- "Ricky and Fred Are TV Fans"
episode #79- "The Million Dollar Idea"
episode #88- "Ricky's Hawaiian Vacation"
episode #103- "Ricky's Movie Offer"
episode #132- "The Great Train Robbery"
episode #153- "Home From Europe"
episode #170- "Lucy Gets Chummy with the Neighbors"
episode #177- "Country Club Dance"

The Lucy-Desi Comedy Hour:
episode #1: "Lucy Takes a Cruise to Havanna"
[cruise director]

And His Final Appearance with Lucy:
The Lucy Show: episode #25- "Lucy Visits the White House" [train conductor]